Furnace



May 29, 1923. 1,456,992

P. J, NUTTING ET Al.

FURNAGE Filed Jun 1. 1921 2 sheets-sheet l May 29, 1923. 1,456,992

P. J. NUTTING ET Ax.

FURNACE Filed June l, 1921 2 Sheets-Sheet `2 Patented May 29, 1923.

UNITED STATES l waage ATENT erica.,

PAUL J. NUTTING, OF WATERTOWN, NEW YORK, AND HENRY WL HAYWARD, OF

MOUNT GILEAD, NORTH CAROLINA, ASSIGNORS T0 DOHERTY RESEARCH COM- PANY, OF NEW YORK, N. Y., A CORPORATION OF DELAWARE.

FURNACE.

Application led J'une 1, 1921.

To all whom. it may con-cern:

Be it known that we, PAUL J. Nm'rING and HENRY W. HAYWARD, citizens of the United States, residing, respectively, at Watertown, in the county of Jefferson and State of New York, and Mount Gilead, 1n the county of Montgomery and State of North Carolina, have invented certam" new and useful Improvements in Furnaces; and we do hereby declare the following to be a full, clear, and exact description of the 1nvention, such' as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to furnaces adapted for use in melting brass and other metals. The invention will be hereinafter described, by way of example, as embodied in an openfiame, gasfired tilting furnace. r,

Open-flame furnaces fired by gaseous or liquid fuel are superior to furnaces of other types in performing many metallurgical operations. In particular, such furnaces eX- cel in their high fuel efficiency and in the speed with which metal may be melted 1n them. The operation of open-flame, fluidfired furnaces as at present constructed is, however. disadvantageous in some of its aspects. For example, in melting brass such furnaces tend to cause rapid volatilization of the zinc as compared with metallurgical furnaces of other types. In melting brass containing less than 20% zinc, however, the tendency of such furnaces toward rapid volatilization is largely or wholly -offset by the greater speed with which metal may be melted in them so that the zinc loss does not materially exceed that in furnaces in which the rate of volatilization is less but in which the brass is melted more slowly. In spite, however, of the relatively high speed with which metal may be melted in them, openflame furnaces of the type now in use are unsuited for melting yellow brass or other alloys containing a high percentage of zinc.

It is an object of this invention to provide a furnace in which metal may be melted very rapidly and in which volatilization of the metal is reduced to a minimum. A more particular object of the invention is to enable brass to be melted in open-flame furnaces with great speed and with small loss of zinc.

Serial N0. 474,188.

To this end an important feature of the invention resides in the provision between the melting chamber of the furnace and a flue for conducting gases from it of means for preventing volatilization of the metal being melted. In the illustrated construction, such means comprises a perforated arch located between the melting chamber and the flue. The arch interposes considerable resistance to the passage of the gases from the furnace and thereby increases the pressure of the gases in the melting chamber to a point such as greatly to reduce volatilization and consequent loss of zinc.

In accordance with a further feature of the invention the furnace is provided with a heat absorbing and radiating element insulated from the top wall of the furnace and serving to increase the speed with which charges of metal can be melted in the furnace. In order to constitute such a heat absorbing element, the perforated arch is made of considerable thickness so as to enable it to absorb a large amount of heat from the gases leaving the furnace. A large .part of the heat absorbed by the arch is radlated to the melting chamber of the furnace at times when the temperature of the melting chamber tends to fall below the temperature of the arch.

A still further feature of the invention resides in the combination with a tiltable furnace having an opening in its front end through which material may be introduced into the furnace and discharged from it, of stationary structure constructed to permit free access to said opening and comprising a stack at the rear end of the furnace arranged to communicate with the furnace in one position, and means for tilting the furnace betweenjisaid position and a position such as to cause the contents of the furnace to be discharged through said opening. Preferably, the furnace stack is designed to operate as a recuperator for preheating the air which is used to support combustion in the furnace. The construction and arrangement of the above-mentioned parts enables the furnace to be operated very eiliciently and with great convenience and safety.

Other subjects and features of the invention, including novel and improved means for conducting gas and air into the combustion chamber of the furnace, will appear as the description proceeds and will be pointed out in the appended claims.

ln the drawings which illustrate a preferred embodiment of the invention,

Fig. 1 is a view in cross-sectional elevation of the furnace and the recuperator taken along the line 1--1 of Fig. 2; and

Fig. 2 is a view in cross-sectional ele`vation of the furnace and the recuperator taken along the line 2-2 of Fig. 1.

The illustrated construction comprises a furnace 10 having an outer casing 12 composed of steel plates and lined on its interior with refractory material. The refractory lining comprises an intermediate layer 14 of fire brick and an inner layer 16 of carborundum brick which constitutes the melting chamber of the furnace. The sides of the furnace are lined with refractory material 18 and are formed to provide chambers 20 and 22 which communicate with the melting chamber of the furnace through burner ports 24. The illustrated furnace, as already indicated, is designed to burnk gaseous fuel, and the chambers 20 and 22 operate as mixing cham-bers for air and gas. The furnace is preferably charged so that the metal when melted will be substantially at the level indicated by the broken line 26 in Fig. 2, and the burner ports 24 are inclined downwardly at an angle such as to concentrate the flame of the burning gas near the center of the charge of metal in the furnace.

It will be apparent from the foregoing that the illustrated furnace is of the open flame type in which the combustion of the fuel is effected in the melting chamber in partial contact with the charge of metal to be melted. It is found that such furnaces when used for melting brass have a tendency to cause relatively rapid volatilization of the zinc. In accordance with this invention means is provided for preventing the zinc from being volatilized so as to cause the composition of the brass to be substan` tially unchanged by the melting operation. As shown, such means comprises an arch 28 located in the upper portion of the furnace and spaced from the top arch 30 of the furnace to provide a flue 32 for conducting gases from the furnace. The arch 28 is formed with perforations 29 so arranged and of such aggregate capacity as to cause the arch 28 to oppose considerable resistance to the passage of gases from the furnace 10 thus increasing the pressure of the gases in the melting chamber to a point such as very largely to prevent volatilization of the zinc. The perforated arch 28 is supported at the sides of the furnace on angle irons 33 (Fig.

2) whichl are in turn riveted to the side walls of the outer steel casing 12, and the top arch 30 of the furnace is laid upon the perforated arch 28. This construction enables the arches 28 and 30 to be readily removed in orderto facilitate the making of repairs in the interiorof the furnace.

The perforated arch 28 is made relatively thick and massive so as to cause it to absorb a large amount of heat from the gases leavin 'the furnace. The flue 32 constitutes a medium for insulating the arch 28 from the top arch of the furnace and causes radiation of heat from the arch 28 to the outside of the furnace to be relatively small. By reason of its large heat absorbing and radiating capacity, the arch 28 tends to equalize the temperature of the furnace, lnasmuch as heat is radiated from it to the melting chamber whenever the temperature of the melting chamber tends to fall below the temperature of the arch. In articular, a large amount of heat is radiate from the arch to the melting chamber when the melting chamber is cooled by the dischar e of a batch of molten metal and the introduction of a new batch of cold metal into the furnace.

In the use of the furnace, the perforated arch 28 shortens the time required for bringing the furnace from a cold state to melting temperature, for the reason that it absorbs heat from the gases, which otherwise would escape from the furnace, and conducts the heat to the walls of the furnace to take the place of heat which would otherwise have been conducted 'to the furnace walls from the melting chamber. The perforated arch is of special advantage, however, in facilitating the heating of the successive charges of metal after the furnace has once been brought to melting temperature, since the arch retains most of its heat during the discharge of metal from the furnace and the admission of a new charge into the furnace and is thus in a condition to radiate a large amount of heat to the new charge.

The perforated arch 28 acts directly to prevent volatilization of the metal being melted by increasing the pressure of the gases in the melting chamber. By reason of the radiation of heat from the arch to the melting chamber, the arch increases the speed with which a charge of metal can be melted and thus also serves indirectly to reduce volatilization of the metal. The effect of the described construction is to enable brass to be melted With small loss, of zinc and to adapt open-flame furnaces for successfully melting brass having a zinc content so high that it could not be melted in openflame furnaces, as formerly constructed, without excessive loss.

The furnace 10 is of the tilting type and isconstructed at its front end with a door (notfshown) and a spout 34 provided with a semi-circular opening through which metal may be charged into and discharged from llO the furnace. The door is closed while char es of metal are being melted'. Attached to t e bottom of the furnace are rails 36 riding on rollers 38 so as to enable the furnace to be readily tilted. A convenient means for tilting the furnace is illustrated in Fig. 1 and comprises a hydraulic cyl1n der 40 connected to a link 42 which is in turn joined to ears 44 projecting rearwardly from the furnace 10.

Associated with the `furnace 10 is a stationary furnace structure comprising a steel frame 46 and a Hue 48 supported on the frame. The stationary furnace structure is disposed at the back of the furnace 10 and is so constructed as to leave the front end of the furnace entirely clear and unobstructed and thus to enable an o rator to charge a batch of metal into the urnace or to observe and direct the discharge of a batch of metal from the furnace with convenience and safety. The Hue 48 is designed to act as a stack for the furnace 10 and is provided with a conduit 50 arranged to communicate with the Hue 32 of the furnace when the furnace is in melting position. Preferably, the conduit 50 is made rectangular, and the rear end of the Hue 32 is built up into rectangular Shape, as indicated at 52. to correspond with the conduit 50.

In order to enable the furnace 10 to be operated at maximum eHiciency and more particularly to allow the high temperatures required for brass melting to be obtained, it is desirable 'that the air for supporting combustion in the furnace shall be preheated. To this end the Hue 48 is designed to operate as a recuperator for pre-heating the air supplied to the furnace. As shown, the Hue 48 contains two radiator columns 54 preferably composed of metal of high heat resisting quality, such, for example, as monel metal and supported on stepped shelves 56 located at the bottom of the Hue 48 on each side of the Hue. Each of the radiator columns 54 is composed of superimposedl sections 58, and each of the sections 58 is in turn made up of a pair of pipes 60. The sections 58 are connected at their ends by short vertical pipes 61. The Haine temperature which gas will naturally develop may be increased directly in proportion to the amount of pre-heating of the air in the radiator columns 54.

Air is conducted to the radiator columns 54 by a pipe 62 and branch pi s 63 and Hows downwardly through the pipes 6l and in alternate directions through the adjacent sections 58 of the radiator columns. rI`he air which is pre-heated in one of the columns 54 is conducted to the right side of the furnace 10 (Fig. 2) by the pipe 64, and the air i from the other radiator column is conducted to the left side of the furnace by a pipe 66.

with short pipes 68 and 70 by'turn-joints 72 disposed in alinement with the axis of oscillation of the furnace. 'The turn-joints 72 enable the air connections to adapt themselves to the .tilting movements o'f the furnace. 4The pipes 68 and 70 conduct the air to headers 74, and rojecting from the headers 74 are pipes 7,6 seated in the side walls of the furnace and communicating with the mixing chambers 2O and 22. The pipes 76 are equal in number to the burner ports 24 and are arranged in substantial alinement with the outer ends of the ports 24.

Gas 1s conducted to the furnace by pipes 78 which lead to headers 80 from which project pipes 82 extending through the side walls of the furnace to the chambers 20 and 22. The pipes 82 correspond in number to the pipes 76 and are disposed directly below the pipes 76. Accordingly, the pipes 82.0pen into the chambers 20 and 22 opposite from the burner ports 24. The pipes 82 are inclined upwardly so as to direct the gas with the air from the pipes 76 into the upper ends of the burner ports 24. In order to lallow for the tilting movements of the furnace, the headers 80 are connected with the pipes g8 by swing joints 84.

When a charge of metal is being melted the furnace occupies the position shown in full lines in Fig. 1. In this position of the furnace, the Hue 32 is in communication with the furnace stack 48. When the charge of metal has been meltedythe hydraulic cylinder 40 is operated to tilt the furnace from full line position to broken line position. The furnace is so constructed that all of its contents will be discharged when it is moved to broken line position. In moving the furnace to discharging position the Hue 32 is carried out of alinement with the Hue 48, but when the furnace has been recharged and is moved back again to melting position, the Hue 32 is again aligned with the recuperator so that the gases given off from the furnace during the melting operation will be conducted through the recuperator.

Having fully described the invention what is claimed is:

1. In an apparatus of the class described, a tiltable furnace formed to provide a Hue in its upper portion and having a spout at its front end through which material may be introduced into it and discharged from it, a recuperator at the rear end of the furnace arranged to communicate with said Hue in one position of the furnace, means for conducting pre-heated air from the recuperator to the furnace, and means for tilting the furnace between a position in which the Hue communicates with the recuperator and a position such as to cause the contents of 'the furnace to be discharged through said spout.

2. In an apparatus of the class described, a tiltable furnace having a spout at its front aoA end and an outlet for gases in its upper portion, and a perforated arch located above the material com artment of the furnace, and spaced from t e top wall of the furnace to provide a flue communicating with said outlet.

3. In an apparatus of the class described, a tiltable furnace having a spout at its front end, means for introducing fluid fuel into the furnace through its side walls, a recuperator at the rear end of the furnace for pre-heating the air which is used to support the combustion of the fuel in the furnace, an outlet for ases from the furnace, and means for disc arging the furnace contents by tilting thc furnace between a registering and a non-registering position of the said outlet with the said recuperator.

4. In an apparatus of the class described, a tiltable furnace having an opening in its front end7 a reeuperator associated with the furnace and arranged to communicate with the interior of the furnace in one posi- A tion of the -furnace, headers on o posite sides of the furnace, means for con ucting pre-heated air from the recuperator to said headers, means for conducting air from the headers to the furnace, means for supplying Huid fuel to the furnace, turn-joints for said headers located in line with the axis of oscillation of the furnace, and means for tilting the furnace between the position in which it communicates with the recuperator to a position such as to cause the contents of the furnace to be discharged through said opening.

5. In an apparatus of the class described, a tiltable furnace formed to rovide air and gas mixing chambers in its side walls and a series of openings for conducting air and gas from the mixing chambers into the combustion chamber of the furnace, separate air and gas headers at each side of the furnace, means for conducting air and gas separately from the headers to the mixmg chambers, and means for conducting air and gas to the headers, constructed to adapt itself to the tiltin movements of the furnace.

6. In an apparatus of the class described, a tiltable furnace formed to provide air and gas mixing chambers in its side walls and a series of openings arranged in a substantially horizontal row and inclined downwardly from the mixing chambers to the combustion chamber of the furnace so as to direct the ame of the gas upon the material in the furnace, separate air and gas headers at each side of the furnace, means for conducting air and gas separately from Lacasse furnace, and means for separatel introducing air and gas into the mlxing c ambers at polnts opposite from said openings.

8. In an apparatus of the class described, a tiltable furnace formed to rovide air and gas vmixing chambers in its side walls and a series of openings inclined downwardly from the mixing chambers to the combustion chamber of the furnace so as to direct the flame o f the as upon the material in the furnace, air an gas headers at the sides of the furnace, a ser1es of pipes for conducting air to the mixing chambers from the air headers, a second series of pipes for conductin gas from the gas headers to the mixing c ambers, and piping for conducting air and gas to the headers, constructed to adapt itself to the tilting movements of the furnace.

9. In an apparatus of the class described, the combination with a furnace formed to provide a melting chamber and a flue for conductin gases from the furnace of means inte ose between the melting chamber and the ue for preventing volatilization of the metal being melted.

10. In an apparatus of the class described, a brass melting furnace formed to provide a flue at its upper end for conducting ses from the furnace, and a perforated arc interposed between the melting chamber of the furnace and the flue and operating to prevent volatilization of the zmc in the brass so as to reserve the composition of the brass substantially unchanged while it is being melted.

11. In an apparatus of the class described, a brass melting furnace, a heat-absorbingelement located in the u per rtion of the furnace and insulated om t e top wall of the furnace, and perforations in the said element of such aggregate area as to interpose resistance to the gases passing therethrough and thereby to decrease metal volatilization.

In testimony whereof we afiix our signatures. PAUL J. NUTTING.

HENRY W. HAYWARD. 

